Questions tagged [radio-frequency]

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How to simply explain correlation between Range, Power and Bandwidth in RF Technologies?

First off, I don't have a great understanding about the physics behind radio frequency technologies. I'm working on a paper evaluating if LoRa infrastructure can help developing communities for a ...
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measure/ visualise high frequencies [closed]

My neigbhor somehow generates high frequencies/ low frequencies and directing them to our flat. We don't really hear a sound but can feel the tingling in the fingers and soles. Whenever this happens I ...
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Complex reflection coefficient for a radio frequency wave

With an RF transmitter at location $P_1$ and a receiver at $P_2$, I would like to calculate how much power reaches $P_2$ via a reflection at a point $P_3$. Hence I need to know the reflection ...
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113 views

Proxima Centauri radio signal

I have recently seen an article about an unusual radio signal coming from Proxima Centauri region. I understand there is a debate around the nature of this signal. My question is related to this ...
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How does UWB enable much higher positioning accuracies than Narrowband

literature and internet articles often only explain UWB’s much higher positioning accuracies with its much higher bandwidth compared to the bandwidth of other narrowband technologies such as WiFi/...
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Is it possible to filter radio-waves using another radio telescope?

When making an observation using a radio telescope, is it possible to filter out noise coming out from a known source by using another telescope that will focus on that noise source? By filtering, I ...
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How does oxygen react to radio waves at 60Ghz?

Since there are 3 states of oxygen: 3Σ−g: The ground triplet state 1Δg: The ground singlet state 1Σ+g: An excited singlet state. What happens to the ground triplet state when it is exposed to the 60 ...
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How to compute the signal propagation loss from each position in a map to one particular receiver location?

I have read up on signal propagation models and RF simulation software. Most software I found computes the path loss for a transmitter at a particular position to each position in the map. I now want ...
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Klystron beam current versus cavity wall current

is there any way to estimate (because it cannot be directly measured) the RF cavity wall current in a Klystron output cavity? It is related to the electron beam current and I have even seen a formula ...
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24 views

Frequency modulation with a certain bandwidth

I came across this sentence in this paper. Alternatively, we modulate the frequency of the microwave excitation voltage at 971 Hz with a square wave and a bandwidth of 32MHz. In my limited FM ...
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1answer
65 views

Modulation Index of an AM wave

I have been given a question as RMS value of an RF(Radio Frequency) voltage after amplitude modulation to a depth of $50$% by a sinusoidal voltage is $80$ Volts. Calculate the RMS value of modulated ...
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How does Tx Power affect the Free Space Path Loss model?

On this website one can use the FSPL model to calculate the Path Loss. This is typically interpreted online as the theoretical signal strength (in dB) that one may receive (e.g. from some WiFi). ...
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How much does the sun emits in the radio spectrum, compared to artificial (human) emissions?

I would like to compare natural vs artificial (human) emissions in the radio spectrum (f < 1 THz). The goal is to bring some scientific facts in the debate for deployment of 5G. It's easy to find ...
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In what media the speed of light is slower than the speed of radio waves, if any?

In what media the speed of visible light is slower than the speed of radio waves, if any? Particles can be faster than visible light, but other electromagnetic waves?
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S-matrix for 2-port network

Consider an impedance $Z$ on a waveguide of impedance $Z_0$. I add a load $Z_L$ at the end of the line but I don't think it should enter in the calculation ? I call $1$ the left port, $2$ the right ...
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Surface Roughness of a material in CST

I am adding an aluminium with a rough surface in CST Studio, but there is only thickness input (how thick the rough surface is), but as per ISO standards they are different types of rough surface with ...
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Ferrite material in CST Studio

I want to add a ferrite material in CST Studio for shielding effectiveness simulations, but not able to find any dispersion data for the material. I want to add a ferrite material in CST Studio for ...
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Will a sheet of carbon atoms reflect radio waves?

I am working out some details in a SciFi novel. I'm thinking of having spec ops who would use a device that could manipulate carbon atoms to form and maintain large, rigid, one-atom thick carbon ...
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1answer
28 views

How I simulate this in CST Studio? [closed]

I am trying to simulate this coaxial transmission line setup for EMI shielding. Placed the Aluminium sample as seen below (in the middle). I am new on this software, learned simulating the coaxial ...
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Intuitive explanation of Nyquist rate?

Is there an intuitive way to understand Nyquist rate (i.e., that, in order to prevent loss, an analog signal must be digitized at a rate twice as high as the highest frequency component of the signal)....
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How to calculate resolution given sampling rate/size?

In a research paper documenting the analog to digital conversion process of an experiment’s radio receiver, the following is written: The station consists of 10 channels. Each channel writes 1 ...
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Inferring angle of source?

Given the relative distance of 3 radio antennae, I want to infer an incident angle for some radio source seen by all 3 antennae, which I know to be on the ground. All I know is the relative locations ...
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1answer
38 views

What does it take to build an effective Faraday cage at bedroom-scale? [closed]

I want to block all EMF transmissions -- tv, radio, cell phone, wifi etcetera. I'm not trying to protect myself from an atmospheric detonation or solar storms, just the RF / EM "noise" of ...
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Monotonicity of sum of two Fresnel Integrals

This question is cross posted on Math Stack Exchange https://math.stackexchange.com/questions/3747009/monotonicity-of-sum-of-two-fresnel-integrals I am studying single-knife edge diffraction of radio ...
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Why is the transmission data rate between Mars and Earth so low?

I read that we get between 500 and 32k bits per second when sending data from Mars to Earth. Apparently it's substantially higher between Moon and Earth. What are the reasons? Please explain the ...
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What is “spectral turnover”?

In a paper which deals with the spectra of radio frequency cosmic events, the word “spectral turnover” is used. What is “spectral turnover”?
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Estimation of power of received radio signal

I would like to estimate the magnitude of a radio signal received from a transmitter by first principles: Transmitter antenna length $L=1$ m Transmitter antenna cross-sectional area $A=1\hbox{ cm}^2$ ...
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How can I calculate “temporal parallax”?

A radio transient was observed by an observatory. I know the observatory’s location, the pointing center of the beam in galactic coordinates and right ascension/declination, and the exact time the ...
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What is the “single pulse radiometer equation”?

This document https://arxiv.org/pdf/1601.03547.pdf refers to the “single pulse radiometer equation”. Apparently, it’s used to calculate the flux of radio transients. What is the “single pulse ...
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25 views

Is there a way to measure flux indirectly?

Is it possible to calculate the flux of some electromagnetic radiation (say, a radio wave) using other parameters?
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Do the free electrons causing the dispersion in the 'Dispersion Measure' of an FRB refract or re-emit the long-wavelength RF waves?

If the free electrons in the interstellar and intergalactic medium absorb then elastically re-emit the longer-wavelength radio waves coming from an FRB, that would reduce their power, because they are ...
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Why are low-frequency radio transients so rare?

Why are low-frequency radio transient (fast radio bursts, etc) so rare? Is it due to our observational equipment, or something intrinsic to transient phenomena?
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How is the “intensity” of a fast radio burst measured?

I’ve read that Fast Radio Bursts are very “intense”, but how is intensity measured?
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Can I calculate frequency limits using bandwidth and center frequency?

I’m given the centre frequency and bandwidth of a radio transient. I need to determine the frequencies over which the transient occurred. I know there’s a relationship between the two, but I’ve ...
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86 views

What’s the difference between FoV and IFoV?

I read that radio telescopes have “huge fields of view (FoV)”, but are unable to precisely localized objects due to their “small instantaneous field of view (IFoV)”. Apparently, somehow the size of ...
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Why do high frequency radio telescope observations require precise localization?

Why do high frequency radio observations, particularly of transient phenomenon such as Fast Radio Burst and Pulsars, require increasingly precise localization with increasingly high frequency?
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Why is all the information contained in the sidebands?

Why is all the information contained only in the sidebands in AM? (And what is this supposed to mean? I read it off a textbook.) Also, why does an increase in bandwidth lead to an increase in quality ...
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Do terms like 'radiowave', 'ultraviolet', 'X-ray' mean the same thing in matter vs in vacuum/air?

I usually use terms like 'radiowave', 'microwave', 'X-ray', etc. to refer to ranges of electromagnetic (EM) frequencies ($f=2\pi/\omega$) or wavelengths ($\lambda = 2\pi/k$) in air or in a vacuum, ...
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Why X-ray and radio waves can penetrate walls but light can not? [duplicate]

Why can visible light, which lies in the middle between X-ray and radio waves in terms of frequency/energy, not penetrate walls?
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How to calculate Doppler Shift for multipaths from moving objects?

Let's say we have a radar where the transmitter and receiver are placed together, and form an angle theta with a target object moving with velocity ...
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Are X galaxies (PKS 2014-55) collisions?

Recent radio imaging by Meerkat of PKS2014-55 show an xshaped galaxy with a distinctive core and lobes. https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&q=Pks+2014+meerkat&btnG=#d=...
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Long Range - High Frequency or Low Frequency

I have a confusion regarding which signal covers more distance - high frequency signal or low frequency signal? My understanding - high frequency signal has high energy. So, it has the energy to ...
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114 views

Does modulating a laser source change its color?

Hopefully you guys can solve this hypothetical for me. Suppose I have a laser which emits light at frequency $530\mathrm{THz}$ with a very narrow spectral width $1\mathrm{Hz}$. From signal theory, ...
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16 views

Simplified model of antenna polarization loss

I need to write a very simple model to estimate the $dB$ value of the polarization loss between two antennas (in realtime). Such antennas are common (yet identical) omnidirectional dipole antennas, ...
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Number of photons collected by a telescope [closed]

I’m trying to calculate how many photons of frequency $1420$ Mhz are collected by a telescope of area $100$ m$^2$ per second from the Andromeda Galaxy, which is 2 million light years away and has a ...
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How does computer identify routers differently? [closed]

Every router has its own name. What is physics that use in making router ideal one from another? Why we can't use same password to access all the routers? I know it sounds crazy but they all use 5GHz ...
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37 views

How to read a meter for radio and microwaves?

I am not clear on how to read this meter for radio waves and microwaves. The bottom band shows it measures from .01 to 1. First, I'm not sure what the units mean (mW/cm2). Radio waves are from 30KHz-...
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What piece of technology is able to record the exact phase of microwaves?

I read that in VLBI, the signals of microwaves are recorded and then later combined. A famous example of this is the Event Horizon Telescope which imaged the black hole. Presumably, the telescopes ...
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How far can an x-ray travel through water?

I am studying x-ray's and how they interact with different mediums, but I am a bit confused on the distances an x-ray can travel through different mediums such as water. Let's take an x-ray with 3 ...
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Commercial Radio Bandwidths around the world

I'm a liberal arts person who has more than a passing interest in radio but it has taken years for this to dawn on me, so be kind if it is obvious. I was out of the US recently, and I saw a radio in ...

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